How can I determine when colliders of two gameobjects touch one another?

I stop gameobjects from colliding with one another by having box colliders around the gameobjects with dimensions bigger than the gameobjects. It works fine, but I want that when the gameobjects collide with one another, they stop moving. I cannot use OnTriggerEnter as I have turned IsTrigger off. Is there a thing which can determine when two gameobjects' collider touch each other?

OnCollisionEnter(Collision collision) fires when two colliders enter collision (similar to OnTriggerEnter but for non-trigger interactions), provided that the moving collider has a Rigidbody attached.