HoloLens 2 offers an exciting and powerful new input: Eye tracking! Eye tracking enables users to quickly and effortlessly engage with holograms across their view and can make your system smarter by better identifying a user's intention. Check out Microsoft's Mixed Reality documentation on eye tracking on HoloLens 2 for more details, such as explaining powerful applications and design guidelines for eye tracking in mixed reality.
New to eye tracking? No problem! There are a number of videos, tutorials and samples to get you started in the Mixed Reality Toolkit! It is recommended to start by exploring some of the existing eye tracking samples that demonstrate best practices for eye-based interactions. You can then use these samples to pull the parts that seem relevant to you into your app. Finally, we also describe how to set up a fresh scene with the core components to get eye tracking working in your app.