Click and key sounds
With nothing selected, open the Motion tab and scroll to CLICK AND KEY SOUNDS.
Click sounds puts a soft tick wherever you clicked. Key sounds puts a quieter one wherever you typed. Volume sets how loud both are.
They are placed from the recorded list of clicks and key presses, so they land exactly on the moment, every time, without you doing anything.
Where the sound comes from
There is no sample file. The tick is generated by arithmetic each time it is needed, which is why the app has no folder of sound effects in it and why the sounds cannot go missing.
When to leave it off
If your microphone already picked up your real keyboard. You will get two clicks slightly out of step with each other, which sounds worse than either alone.
On a long video. A tick on every one of four hundred key presses stops being a helpful cue and becomes a woodpecker.
It is at its best on a short piece where the point is what is being clicked: a product demonstration, a tutorial about a shortcut, anything under a minute.