input manager

Unity have actually documented this really well here  You might want to use the CrossPlatformInputManager which I have made a blog post about here  

To use the cross platform input manager you need to make sure you have the Standard Assets Package included in your Unity project. To import it, use these instructions https://docs.unity3d.com/560/Documentation/Manual/AssetPackages.html Ensure that CrossPlatformInput is selected in both the “Editor” and “Standard Assets” folders. Open up the Project Setting > Inputs to define all of the … Read more