Get axis literal keyboard or mouse value... not possible?

Hi all,

I have a dire need: I need to know which key or mouse button is actually associated with an axis.

Quite simply, we all can get into input manager and define a new axis, for example 'myaxisname' with a positive button of mouse1, and then we can use

 Input.GetAxis("myaxisname")

to check if the axis is in use or not, but how about the actual button/ key associated with said axis? I haven't been able to find any reference to it. It's quite certain that despite my multiple reads of the guide, I haven't been able to 'extract' mouse1 from Input.GetAxis("myaxisname")

What I'm trying to achieve is basically

 GUILayout.Label("Press " + whats_the_button_of("myaxisname") + " to use");