How to achieve Dynamic Gizmo DrawLine()

Hello Everybody. I'm pleased to meet you all. I'm currently working on a tool similar to this

I have managed to draw a line between each instantiated level prefab but I have no idea how to make it dynamic. Readjust the lines connected to an object if this object is moved in the scene ,just like in the above video.

The reason why I don't buy that tool directly is I wish to learn how it is made because i believe it offers great learning value Any help in any form would be greatly appreaciated