Can a probation officer request an serve a serch warent on someone that is not on probation?

First of all, it sounds as though you have been victimized by some kind of "cowboy" Probation Officer. It is clearly not a Probation Officer's duty to seek, obtain and serve search warrants for non-probationers. Law enforcement can do so if they properly apply for the warrant and there is probable cause for its issuance. You did not mention whether or not the search yielded any incriminating evidence. However, you can challenge the search with a Penal Code section 1538.5 motion, alleging lack of probable cause or false information,and move to disclose the name of the informant (Hobbs and 'traverse and quash' the warrant. Then, any evidence found would be suppressed, and the case dismissed (the D.A. would have no other choice).

Any properly issued search warrant can be executed by law enforcement. If you were arrested, then you can fight it. You can raise all available defenses with whatever admissible and credible witnesses, evidence and facts are available for legal arguments for various suppression motions, plea-bargaining or at trial. If you don't know how to do these things, then hire an attorney that does, who will try to get a decent plea bargain for you. If serious about doing so, feel free to contact me.

You should sit down and discuss your case with an attorney. Warrants have to be signed by a judge. Your attorney will be able to review if it is a valid warrant.