Use the attached file. This may help.
Answered with a tutorial: https://grabcad.com/tutorials/how-to-model-a-mouse-in-a-catia
Lay down a piece of cheese, wait for the mouse...take a picture..
Than draw the mouse in 3d....
Serious...lots of tutorial to be found as Arestide Stated.
But it is not the mouse that you need....I think it is more about learning to use your 3D software....if you master the basics than it is possible to model almost everything.....every model comes down to the same thing...sketching and extruding, cutting, patterning etc.