I answered this in another thread you were commenting on but i’ll do it again here in case you missed it but Version 1 Google cardboard, the one with the magnet, is no longer supported by the GoogleVR sdk so that’s probably why you can’t find ways to access it.
You should develop for v2 Cardboard - the one with the button - which is as easy as listening for touch input.
As an FYI this is the version of the SDK where they dropped support for v1 cardboard towards the end of last year.