What do you do? These objects are considered obstructions (Rule 24), and you're entitled to relief without penalty if your ball, stance or swing is interfered with by an obstruction.
Some yardage posts, for example, can easily be moved. If you can move the obstruction, and your ball isn't touching it, move the object and play on. If your ball moves specifically because of the movement of the obstruction, you can replace the ball without penalty.