Defining a Hyper Key · GitBook — BetterTouchTool (starting with version 3.540) allows you to use Caps Lock as a Hyper Key. A Hyper Key is a magical key which automatically presses all the standard modifiers (ctrl+shift+cmd+opt).
Why would you need that? Because on macOS many of the easy to reach shortcut combinations are already used by the system or by some app. By using the Hyper Key can can define shortcuts in BTT that are pretty much guaranteed to not be used anywhere else (who would want to press e.g. ctrl+shift+cmd+opt+ P). This makes room for tons of easy to remember and easy to use shortcuts.