You should always have an understanding of recording consent laws in your state/country and if you live somewhere with one party consent, you should always secretly record HR conversations. Just as long as it’s not obvious you can do a lot of things with your phone. Company policy might ding you for exercising your rights; that’s their right. If you’re building a case against the company that should be the least of your worries. Know your rights and more importantly pretend you don’t know them.