Should I ask a candidate about their time in high school?

For most candidates, no. Spend the interview time on the most recent and most relevant chapters of their career.

For entry-level roles and candidates with minimal job experience, yes. Their time in high school, university or graduate school may be the best evidence you have. Treat each of those periods as a chapter, and ask the same structured questions about it: why they chose it, what success looked like, how they performed, their biggest accomplishments and their biggest mistakes, and how a teacher, coach or manager from that time would describe them.

HireBest includes standard templates for these chapters: Early Years, High School, University and Grad School. Choose the ones you need for the job under Settings → Interview Rounds. See What are the job settings?