Hi @jiayang, of course! In fact, if you wish to develop for Unity there we have already dedicated SDK’s for this purpose that do not require either the Core SDK or the Pro SDK.
For the Tobii Tech consumer range of eye trackers such as the Tobii 4C & EyeX, there is available the Tobii Unity SDK for Desktop for which you can download and read further information @ https://developer.tobii.com/tobii-unity-sdk/
If however you possess a Tobii Pro eye tracker such as TX300, X60, etc then you can use the Unity Bindings of the Pro SDK which you can read more about @ http://developer.tobiipro.com/unity/unity-getting-started.html
Hopefully this answers your question, please let us know if we can be of any further assistance.