Pole barns should NOT get out of square doors and windows due to frost heave... unless... the footers weren't deep enough.
at which point, there's simply no fixing it. Sorry to hear that.
What are your weather concerns? Earthquake? Tornado? Hurricane? Flooding?
What is your ground like? Sand? Clay? Rock? Flat? Uneven? Sloped significantly?
What are your predators like - both ground and underground? Termites? Rats? Snakes? Fox? Trash Panda?
What's the material at the base...