Record the sound of white noise combined with an ultra high frequency piercing noise - a rape alarm is good too - and then ensure that you are close enough to him when he lifts up the cone play the sound REALLY LOUD - if his nose is bleeding and blood is coming out of his ears you know he has heard it . After this he will never dare lift the parking cone again . You can though and stick a fully taxed and MOT'd JCB in said parking space - Job done .