Is there something you can use to put underneath normal pans to use on induction hob?

Yes, you can use an induction interface disc to enable normal (non-magnetic) pans to work on an induction hob. This disc is placed between the induction cooktop and the pan, generating a magnetic field that allows the induction hob to heat the pan. It's a practical solution for using traditional cookware on induction surfaces, but keep in mind that it may not be as efficient as using induction-compatible pans.