How do I read and handle input from a mobile device?

I need to force the player's input type to thumbstick. I also need to change the image on the jump button and change what happens when it is pressed.

I'm assuming the thumbstick will return an input delta between 0 and 1?

The real problem is that I'm not sure how to access any of these.

I have looked on the wiki but failed to find anything. Probably because I don't know exactly what to look for. Any information would be helpful. A wiki link, examples, etc.

Thanks ahead of time!