you have 2 coordinates of the shape position.
you have also the size of the shape
You have the coordinates of the mouse position
If mouse.X is between shape.X and shape.X+shape.Width and mouse.Y is
equal to shape.Y or shape.Y+shape.Heigh and so on for a rectangle
For different but "regular" shapes you should calculate it in a
For complex and irregular shape you should discompose it to smal pieces
and do the same calculation:
check this: determine
if a point sits inside an arbitrary shape?
If the shape can be converted to a bitmap another way could be to check
for pixel color but this will work only if the shape edge color are
different from other pixel in the shape