If your cat is a real escape artist, you may want to invest in the Oscillot cat containment system.
Made in Australia, this ingenious attachment screws into the top of any fence and instantly makes it impossible for cats to climb over. It's basically a long metal bar that turns in place, so when your pet tries to pull themselves up the Oscillot rotates and they drop harmlessly back on your side of the fence.
This invention has been endorsed by Australia's Animal Welfare League, and it may even help your cat live longer by keeping them safely in your property.
If you're interested in putting your own cat in lock-down, you can order the Oscillot online. Otherwise, have fun chasing it around the neighborhood, because cats are bound to make a run for freedom eventually.