There are plenty of things to see in Pompeii but you may miss them if you don't have a tour guide.
We booked a private tour of Pompeii with Raffaele, an archaeologist from Naples. You can book a similar tour by visiting https://www.naplesgrandtour.com/
Pompeii is a popular place to visit from Naples and is only a short journey from Naples Cruise Port. It's impossible to see the whole of Pompeii in one day but you can see many of the key features and landmarks.