Yeah there is a thing that is used to catch the pin if the hitch isn't latched but you really shouldn't need it. I don't know what hitch you have but on my Reese there are a couple of things I do to insure the hitch is locked.
First latch the hitch around the pin and clost the handle. If the handle won't close it isn't latched. My handle has a latch that you move down to insure the handle is far enough in. Now I take a flash light and go to the back of the truck and make sure I visualy see the jaws clamped around the pin. Now raise the landing gear until the legs are only an inch off the ground. Now leave the wheels on the trailer chocked and get back into the truck and try to pull away just a bit putting pressure on the hitch. If the thing holds your fine. If not the camper will only fall one inch. If the latch one the handle will lock and you see the jaws of the hitch around the pin your locked in.