I wanted to write that the use of eye tracking mechanism in phones will be common in a couple of years, but I decided to search online to check if there was anything on the topic. And here is an excellent study, with an analysis of options and ready solutions.
https://medium.com/@taolu_99738/developing-of-eye-tracking-application-for-smartphone-b875c50ee0c3
Hi, I'm Rauf Aliev. 