Put it in expectations, quantify it, and reward it at performance reviews. In a self-review, I should be able to write that I took Andrew Ng's Coursera ML course and be rewarded for how that makes me a more valuable team member. On the employee end, I should be able to explain what I learned, how it increases my value to the team, and how I've applied or will apply it.

Too often, companies "expect" their employees to take advantage of the fact that they allow them to learn on the job, but only reward short-term performance.