If you hear it only when releasing the brake pedal, it is likely caused by the rear brake shoes sliding on the backing plates. The fix is to place a small amount of grease on the six "lands" the shoes sit on. Those are the six raised spots on each backing plate. Dodge Caravans had that noise in the late '80s to 1995 models. Fingerprint grease was almost enough grease to quiet the noise. Axle bearing grease and Spray White Lube work well. That will stop the squeak for a year or two.