Metronom

Depends on how you've recorded the track, and where you have the metronome routed to. If you use a mic in the room, and play the metronome through a speaker, then obviously you'll hear it. But if you have it routed to an external output, and this is routed back through your sound device so that it appears as an available input, then yes it will record. You need to describe exactly how you are working before we can say definitively which it is - because normally it's muted in any mixdown or export.