can they have me arrested if they don't get what they want
See, this is where you messed up.
You are on probation.
Its standard practice that if you get offered probation (and accept it, they can't force probation on you) you agree to NOT break any laws, stay away from illegal drugs, possess no weapons, and break no laws.
There are many more conditions, but you need not worry about the small (or large) quantity of drugs they found in your possession.
You need to focus on NOT being violated.
If you get violated, you'll get a hearing about revoking your probation.
So, here's how to play this BAD hand.
For the next couple of weeks, fly low, stay off their radar.
Obey the law, walk that line.
If they come, they come.
You can say, I want to exercise my right to remain silent and ask for a lawyer.
Then just shut up.
You can't control anything.
You gave them your power when you messed yourself up by doing you know what.
You'll eventually get a hearing on a probation violation, be arraigned on a new NOTHING small drug beef, or nothing will happen until you next see your PO. Then your PO will give you a lecture.
By the way, you are required to report ALL police contacts to your PO. Do that before they do.
Then you wait and keep your trap shut.