Pro Tools | First Main Windows : Transport Window : MIDI Controls : Metronome Click
 
Metronome Click
When selected, Pro Tools generates a metronome pulse that can be set to trigger built-in sounds or MIDI instruments during playback and recording.
The Pro Tools metronome is configured in the Click/Countoff Options dialog. Double-click the Metronome Click button to open the Click/Countoff Options dialog.