I pull the airlock out of my bucket and sample through that hole but I do not know if that would work for you.
I just open the lid and take a sample.
I find it easier to pull the lock because the lid is kind of hard to get off (that sounds super dirty sorry
)
but if the theif didn't fit in the hole (again... sorry) I would also pull the lid. Not a safety or sanitation issue just being pragmatic!