I'm assuming this is talking about the revised numbers for 2025? And if that revised so heavily downward, hard to imagine the latest numbers are somehow more stable?
The same way that anyone would: they conduct a statistical sample and report unemployment numbers based on that. Source: 15 years ago I was one of the people they contacted. As I recall, a letter came to our apartment, asking for the adult (18+) who had their birthday closest to that date to contact them and provide a phone number and some basic demographic data. That was me, not my roommate, so for the next 12 months I got a call once a month asking me for my employment details about a specific week that month- had I been looking for a job, was I still employed, etc.