Collider Layers?

Is there some way in C# that I can set Collider layers? I have two Colliders on a game object, the larger one makes a sphere around the object and the second is a collider of the object. When the player enters the larger one, it activates a FSM machine. When the mouse enters the object collider it should return the distance to the target. However, It detects the OnMouseEnter event for the larger sphere instead. Any advice?

Make sure the two colliders are attached to different game objects and set the layer of the larger collider to Ignore Raycast.