I am using a freshly installed Ubuntu-Gnome 16.04, and I want to set caps-lock to change keyboard layout (single key, not key combination). I used to have this Linux-mint, and I grew used to it. I looked into the setting manager, but there is doesn't accept caps-lock as a valid input. I also looked int gnome-tweak-tools but there I can't find the keyboard layout switching at all. Is this possible? how?
How to allow for caps-lock keyboard layout change
keyboard shortcuts;gnome3;keyboard layout
You can do that via System Settings > Keyboard (or gnome-control-center keyboard in terminal): go to Typing and set Modifiers-only switch to next source to Caps LockAlternatively, set the corresponding xkb option (which is what the above does underneath) via gsettings or dconf: navigate to org > gnome > desktop > input-sources and add  grp:caps_toggle to your xkb-options:Note each option is enclosed in single quotes, options are separated by comma+space.