Legally? Depends on your locality and jurisdiction. There’s lots of laws that specifically address recording people without their consent.

Since others covered the legal angle and I'm not a lawyer anyway, just thought I'd mention another angle, which is that of having evidence in a dispute, even if it doesn't reach court. I know someone who had an issue at work and they were able to record the audio, which helped them in bringing up the issue to HR (they actually told the person they were gonna do it and the person was like "yeah, record me" 🙃 ).

Cause ya know, without that, it's very easy for someone to deny their part in it after the fact or downplay what they said or did. I've always heard with workplaces that it means little if it's not in writing, probably for similar reasons. But like others said, wise to look up local laws for recording in any case.

As the others said, it depends on the laws of your country.

When I have a juridical question like that, I contact my trade union. They are usually well informed on that subject and if they don't have the answer, they have jurists on hand they can ask.

If you are in public, yes. If not, probably not.

You need to look up your state's recording consent laws, but generally any place where there is "no reasonable expectation of privacy" is considered legal to record audio, even in states that follow "two party consent" frameworks. Depending on the work place, it could be argued one way or the other and only a lawyer familiar with your state's laws could give a sure answer based on the specifics of your situation. A lot of states don't have any limitations on recording though so if you are in one of those you are obviously in the clear.

you should get them to go for a forest walk instead