In language “interrogatives” are words related to asking questions. Who, what, where, when, why are all called interrogatives. It’s definitely a less common us

In language “interrogatives” are words related to asking questions. Who, what, where, when, why are all called interrogatives. It’s definitely a less common usage but as you say it has the sense of questing or probing or feeling out. For me it belongs to a higher register of language, it’s a word I might use in that sense when writing a report or a formal email or something of that nature.