Probation officers have the authority to make unannounced house visits and they often do. I'm not sure why you would not want to tell the probation officer that your moved. If you moved out of the jurisdiction, they are usually more than happy to transfer the probation to that location. Contact an attorney ASAP to discuss this issue.
There are a myriad of reasons as to how your PO found out. You could have avoided this by just telling him. Now, you face serious consequences and should hire an attorney.
The answer provided is for general information purposes and cannot be relied upon. In order to provide legal advice, one must engage with a live attorney; this answer does not create such attorney-client relationship.
The PO can and often will make unannounced house visits, my suggestion is you speak with a criminal defense attorney before making any decisions as to what to do next.
The above answer is for information only; and does NOT constitute legal advice. This answer does not constitute, nor does it create, an attorney-client relationship between KaplunMarx, PLLC, Theodor Kapun and any receiver. The information provided on these pages is general only, and you should not act upon this information without consulting with a qualified attorney.