Detail this asset from Unity Store: Original Link
This is a paid asset, but now you can download Head Tracking Camera for Smart Phone Free.
Head Tracking Camera for Smart Phone v1.0.1
“Head Tracking Camera” is Unity Plug-In to realize the head tracking control for mobile(smart phone) to viewing VR content.
Main features :
* Controlling the camera automatically using each sensor of iOS and Android.
* Switchable On/Off stereogram view.
* Very simple structure, anyone can use right away.
* Unity4.5 / 4.6 / 5.0
* iOS6 or later
* Android4.2 or later
* Additionally, Cardboard SDK is required for Android app build.
(We’ve confirmed working properly at v0.5.1 and v0.5.2.)
Eye Gaze Input