To be more specfic: C:\Users\your user name\Saved Games\DCSwhatever\Config\Input\.
Back up this folder and you're good (this method won't work when moving to another computer, but that's a topic for another discussion).
While we're at it, the whole Saved Games\DCS folder contains all your game settings, records and whatnot, so you might want to back it up anyway.
Last edited by Art_J; 03/08/18 08:31 PM.