Half-price cinema tickets, cycle to work schemes and gym passes have long been part of employee benefits programmes.

But with research showing 84% of millennials look to leave their jobs within the first two years, employers want to tailor their perks packages to their employees' needs.

Emerging technologies such as data analytics, chatbots, and wearables can help employers know which benefits resonate with employees.

And machine learning can monitor take-up and avoid wasting money on unwanted benefits.

"From an employer perspective, there is already a lot more emphasis on looking at data to see what benefits employees are using," says Jeanette Makings, head of financial education at merchant bank Close Brothers.

"This allows them to make better decisions, meaning they can tailor their benefits spend while improving employee engagement".

She says that for some companies "data analytics technology allows them to see who is taking up which offers, as well as what forms of communication are working best.

"This type of information is very valuable and could easily prompt a change in the company's overall benefits strategy."

For example, some companies have changed their gym membership programmes in response to analysis showing another local gym is more popular with their employees.

Online portals and apps have already transformed employee benefits provision over the last 10 years, but are now more sophisticated.

Artificial Intelligence (AI) systems "could help them to avoid wasting money on benefits their employees do not want, and to improve their communications, for example by identifying pockets of the workforce who need an extra nudge to get involved," says Ms Makings.

AI has been used to develop chatbots that can help employees to find information on subjects ranging from mental health to saving for retirement at any time.

"Employees can now use them to access services such as financial advice whenever they want - including at midnight when they are lying in bed," says Ms Makings.

AI is not the only tech being used to improve employee benefits provision, though.

A new generation of hi-tech benefits providers also offering innovative add-on services designed to cater to individual employees' needs.

Faith Howe, a director of talent at global communications agency FleishmanHillard, says: "One of the biggest changes over the last few years has been the breadth of choice of technology available".

One example is Wagestream, which allows employees to access their pay before pay day.

Peter Briffett, chief executive at the UK-based company, says Wagestream uses technology "to tackle the cashflow problems that come with being paid once a month".

"We know that lots of employees face financial stress as a result of this, with many being pushed into taking out high-interest lending.

"Our tech, which calculates how much people can withdraw by looking at how many hours they have worked, aims to prevent this issue."

It comes with a charge: employers pay £1 per employee per month and staff are charged a fixed fee of £1.75 each time they make a withdrawal.

Another example is Open Blend, a management performance tool provider that counts French fashion brand Lacoste among its clients.

It uses Microsoft's Power BI business analytics tool to provide businesses with information about their employees' wellbeing needs.

"Attrition is a huge problem for businesses," says Anna Rasmussen, founder of Open Blend.

"Our research indicates that 84% of millennials look to leave their jobs within the first two years.

"So live data of the kind we can provide because our system is updated each time an employee has a session with his or her manager is very valuable as it shows companies what their employees need to stay motivated and reach their full potential, in real-time."

Employers can even go a step beyond analysing data by tracking employees' movements.

This is where wearable technology comes in.

Health and life insurance provider Vitality, for example, claims its Active Rewards Apple Watch scheme, which is available in 13 countries including Australia and Germany, "helps more than a million members make the most of their health and wealth".

Users of the scheme can earn "rewards" such as discounts on their insurance premiums by tracking their activity with an Apple Watch.

And according to a study conducted by RAND Europe for Vitality last year, combining the two can really get people moving.

The study, which included more than 400,000 people in South Africa, the US, and the UK, found that participants using Vitality Active Rewards in conjunction with an Apple Watch to measure their performance did the equivalent of 4.8 extra days of activity per month.

That's an increase of 34%.

There are concerns about how employers could use wearable device data in the future, though.

"Personally I think monitoring how your staff sleep, for example, is a bit Big Brother," says Ms Rasmussen.

Human resources experts also warn against relying solely on tech for your employee benefits provision.

"Apps, for example, can increase engagement if used in the right way," Ms Howe said.

"But if you don't have a collaborative culture, apps alone won't solve your problems of uptake and engagement.

"At this stage, I think we need greater understanding of the technology coming through, as well as more practical examples to help us understand what works and what doesn't."