Has the neighbour complained to you and told you what noises are concerning him?
The tribunal won’t entertain a general claim of noise.
So knowing what his claim is , keep a diary of when you made the noise.
Also keep a diary of when you or other occupants are at home. If he is making up bogus claims, it’s unlikely he will know when you are at home. Your aim is to discredit his evidence ( at the tribunal)
As for a recording device, I don’t know such a thing exists ( commercially) . You also face the challenge to time stamp audio and if you edit a recording, he will say it’s been doctored.
Also remember that at the tribunal it is up to the claimant to prove their case. You do not have to disprove it, but your aim is to put into question their evidence.