Temporary thermal adhesive for PCB measurement
I've always used Kapton (aka Polyimide) tape for this purpose.

Gell type superglue work too but leaves a slight residue, e.g. BlackTak TackPack type products (wire tacking adhesive).  They do chisel off with a knive if you don't use too much.

You don't say what temperatures you are going to, but I've also used tiny slices of hot melt glue and a hot air gun to melt it.  More for re-working prototype designs but it might work for this too.

It can easily be removed by softening it again and using a larger glue stick to pick it off. Obviously if your surface gets close to the melting temperature then that's no use.