What kind of car are you working on. some vehicles you can pop the top portion of the timming belt cover off with little effort. If it is old enough to have a distributor just pop the cap off have someone crank it over and if the rotor button don't spin it is your belt. If it is a newer car with coil packs you may have to pop the valve cover off and see if the valves are moving, but first take the oil fill cap off and look in there to see if you can see the valves if so no need to take cover off just have someone crank it over while looking in there for movement.

There should be an access cover on the top of your timing belt. Your front cover is usually split into an upper and lower. Remove the upper portion and have someone crank on the engine while you watch and see if the belt and camshaft are turning.