You need to immediately notify your probation officer; they will know anyway because they will receive a report.
They have heard 1000 times the excuse about cough medicine. There is no way to determine what set it off.
I strongly suggest that you be in complete compliance with the balance of your probation and that you not make any additional mistakes.
Although I have answered the question to try to help you, you should consult with a lawyer in your area in person on the matter. In addition, my answer does not establish an attorney-client relationship between us.
Unfortunately, the device (and your PO) only know that it was triggered, not what substance triggered it. Explain to your PO what happened and do all that you can to be conscience of things like this during the remainder of your probation.