I found this on the internet different.
Nail aluminum foil along the top of fence. the shiny reflections scare cats, and they don't like the feel of foil under there paws. This may not stop the cats from getting over fence, but it will deter them from walking along the top of it.
Attach some large ( at least 2 inches in diameter) PVC pipe to the top of the fence. This will make it hard for cats to grip with there claws and since it hangs over the edge of the fence it be harder for them to get over.
Fit a length of string so that it hangs about 1 foot above top edge of the fence, which will discourage cats from trying to wlak there. Orange peels, aluminum foil, or bits of broken CD hung from the string will deter cats futher.
Do not know if this works or not who knows. Good Luck.