If it is an illegal substance, or becomes an illegal.substance while you are on probation, expect to be tested for it. The types of tests vary by county and perhaps even by the amount of.money in the budget.
I agree with the above answer. Usually, probation conditions state that you are not to consume any intoxicating substance. Therefore, it does not matter if the substance is legal (or if the legislature has not yet legalized it). If you are asking in regards to employers, then it depends on the lab and the employer's request. I hope this helps, good luck
In addition to the above responses you could always ask your probation officer. I suggest this with a word of caution because your PO is not there to help you and will be looking for ways to trip you up. If you ask about a substance that IS banned, s/he might test you for it immediately. If on the other hand, you've not smoked it yet and truly want to know if you can, it can't hurt to ask to ensure that you don't violation your terms.