How to parent gameobject at point of collision?

I want to parent a gameobject to another at the point of collision/contact, and I don't know how to. For example of what I want to achieve, it is similar to the Pikmin games, where a gameobject (Pikmin) is thrown onto the top of an other gameobject (enemy). The Pikmin attaches/parents to the enemy at the point of collision/contact.