For certain motives, for some controls I would like to be able to detect if the Secondary button of an Input Button is pressed, can I do this?
In the Edit-> Project Settings-> Input manager, you can assign primary and secondary keys. For instance, Horizontal has left-right key and a-d as default.
If you use “Horizontal” for input it is just checking which one is used and return positive or negative but if you use.
if(Input.GetKey(KeyCode.A))
this will only return true when A (or a obviously) is pressed.
Similarly, you can give the name of a button as
if (Input.GetButtonDown ("Fire1"))
which by default is left ctrl or alternative button is mouse 0. You can check if one or the other is pressed
if (Input.GetKeyDown (KeyCode.LeftControl))
if (Input.GetMouseButtonDown (0))