How do I make physical pivot thing?

Hello, sorry for disturbing but am not sure what to search for in menual…
Anyways I am trying to make an object to move when other object touches it
But I want it to move like a lamp on the ceiling when obj2 touches it:

3267-help.jpg

Check out : Unity - Manual: Configurable Joint component reference

There are several types of joint including fixed, hinged and spring

https://www.google.com.au/search?q=unity+joints