You can just lure them inside with wet food!

We saw this absolutely SCRUNGLY little thing with a paw on our back door, but she bolted when she saw us. I lured her out of hiding with some wet food and a bowl, giving her small amounts at a time and gradually moving it closer to our back porch. She was entirely too young and hungry to be outside (she ate 2 whole cans of wet food at once. Even our fattest of cats are satisfied with one), so we made a plan to trap her. The trap turned out to not be necessary as she got bold after a week and let me sit with her and even pet her a bit! She did get startled and slash me up a little bit (rabies shots are ASS) but she is a sweetheart. Since she kept coming to the door we decided to quarantine our other cats and open it and lure her in with food. It eventually worked and we have her quarantined in the bathroom for now. Sadly we already have 5 cats and their politics are already complicated enough, but we found her a forever home with someone who will spoil her rotten.