Bannaflak just released his free app for facial motion capture on iPhone X.
Here is what it features :
It has been tested with Maya, Lightwave, Houdini and Blender. Cinema 4D and Unreal still have some issue with the app but that will be hopefully fixed in future updates.
Oh, and of course you have to own a $1300 iPhone X. ;)
You can download the app here.