Bad shocks can make a car squeak especially when you go over bumps or are driving down rough roads.
If your car is bouncing when you go over rough roads or speed bumps and the car is squealing then the shocks could be at fault.
A good way to see if the shocks are causing the car to squeak is to push down on the back of the car and see if it goes down easily and then squeaks as you push down on the car.
if the car is squeaking when you push down on the car over and over then it could be the shocks going bad.
Another cause of a car squeaking is bad struts or something rubbing up against the wheel or rubbing when the vehicle is bouncing.
Other causes of a car squeaking are worn ball joints or worn bushings even in the shocks.