You're going to want to put up some secure fencing. Fox are pretty crafty and can climb. I'd also suggest running a few strands of electric fencing around whatever fence you put up. Start about 4" off the ground, another strand 5-6" up from that, and at least one, maybe two more another 5-6" apart. As others have said, now that the fox has found you, it'll keep coming back until they are all gone, or inaccessible. Fox are pretty smart - they can be hard to catch in a live trap.
