Hi! I’m a beginner in Unity and I’m wondering how to make a game like this one:
http://www.ballonastring.com/
I’ve tried hinge joints and some plugins from the asset store based on hinge joints but they do weird stuff.
It’s driving me crazy. Can anyone put me in the right direction? 
Although i cant answer this myself. I have found two pages from a few years back in the unity forum and answers sections. The answers seem to be similar so may help you.
http://forum.unity3d.com/threads/how-to-create-the-thread-with-hanging-ball-with-physics.151867/
Here is a youtube vid as well