The role of the crowbar is the same as that of the lever. It can be used in two ways as shown in the figures.

in the first image, the fulcrum is applied in the middle whereas, in the second image, fulcrum is not applied.

Explanation:

In the left image,

the crowbar turns about the little stone kept beneath it that the enormous stone gets lifted. The point about which a switch turns is known as the 'Fulcrum'.The power we apply is called Effort. The resistive power that is overwhelmed by the exertion is called Resistance. Resistance happens at the position where the heaviness of the enormous stone is experienced.

In the right image,

the force is applied directly to the enormous stone by a crowbar.