Android - Detecting USB Mouse and Keyboard Input

I have Linaro Android 4.4.3 running on a Pandaboard, so I'm using a USB keyboard and mouse to interact with things. I wanted to make a Unity app with basic functionality (so nothing more complex than a single point drag and typing). However, I noticed with at least the basic GUI.Textfield and GUI.Button, that I cannot click them to gain focus. I noticed I can still press tab to get to the textfields, but even while they are in focus I cannot type anything inside.

Is there a way to detect input from these devices over an Android application?