Well you can do several things, if you want to try and catch it to find out if it has a chip or not and possibly find it's owner.
You can either call animal control in your area and see if that will come out, or you can contact them, a local shelter, or even your vet, to see if they might have a cat trap that they are willing to sign out to you on a time basis.
If you go the route of the cat trap, I would get a can of cat food, or something really fish like sardines, and place it in the back of the trap, I would also recommend covering the trap with a sheet or blanket, as cat's seem to be more curious when they can't really see what is in there.
Or you can just try to sit out with some canned food and try to lure the cat your way or do this over several days trying to gain the cat's trust.
If the cat is a stray it might be harder to gain his/her trust, specially if it is feral, but those are the only options I can come up with in trying to help at this time.