My HP ZBook has a keyboard issue (colleague has the same model, same issue after ~2 years, seems really poor quality). It's that the left shift key is intermittingly to mostly failing. So as a work around I would like to use the caps lock key as a replacement for the left shift key. I'm using Debian Stretch with GNOME 3.

I looked through Tweak Tool, "Caps Lock toggles ShiftLock" is mostly what I want, but I don't want to toggle the state, but only hold shift as long as i hold the caps lock key. how can i map the caps lock key to behave exactly like the left shift key?