Hi @ayaataya and thank you for your interest in developing Unity Applications with your Tobii 4C!
As you are new to Developing, then we would suggest you first of all take a look at our introductory video to the Unity SDK @ https://www.youtube.com/watch?v=O-yEwaJc68U
Thereafter, we have created an extensive getting started guide to get up and running quickly @ https://tobii.github.io/UnitySDK/manual#getting-started
With details on capturing the head position data @ https://tobii.github.io/UnitySDK/manual#head-pose-data
Please do go through these and let me know how you get on. Best Wishes.