Our neighbour’s cat used to make a nuisance of itself, so I set a possum trap in the shed, baited with some meat, and after a couple of days caught the cat. It stayed in the shed in the cage for about 24 hours, until the neighbour came over asking whether we’d see her cat, so I discreetly released it. The cat didn’t come back again. No harm done, but it learned the lesson.
I’ve heard cats HATE the smell of vinegar, so if you can catch the feral cat and spray it it with vinegar, it might get the point and stay away.
Possum traps in Australia are for catching and removing possums from roof spaces. They are like a large humane rat trap, a metal cage with a spring loaded door that snaps shut when the possum steps on a baited plate at the other end of the cage.
My grandmother once put a wad of cotton wool on the end of a stick, soaked in turpentine, and dabbed a neighbour’s cat under the tail when it was fishing in her goldfish pond. That cat, too, never came back.