It used to be possible to use a Thermometer (or other small science part) while it was being carried on a Kerbal's back in EVA. Now that is no longer possible and you cannot activate them from the inventory.

This means Kerbals can't do science on EVA unless there is a convenient surface to attach things too. Also, dropping small objects like Thermometers seems to always destroy them, even in Munar gravity.

MonkeyWrench has some configs (updated from KAS to KIS by yours truly) that add KIS modules to small science instruments so that they can be equipped and used without dropping them.

Parts stored in a KIS container don't exist as game objects. And making any science part to be equippable sounds as an overkill.

I drop them on Kerbal's head :) works great