Unity Remote 5, allows you to use your Apple TV to view and test your game live, right inside the Unity Editor without having to build your project. Unity Remote 5 makes your Apple TV act as remote control. It streams all Siri remote or MFi gamepad input info such as touches, button clicks and accelerometer info back to Unity Editor. This is useful for rapid development when you don't want to compile and deploy your project after each change and prefer to use the Unity Editor Game window instead. Unity Remote is compatible with any Unity version newer than 5.0, but some features require Unity 5.4 or above.
Full documentation is available on https://docs.unity3d.com/Manual/UnityRemote5.html