We actually have a backpack just for geocaching which holds the following...
Notebook, cell car charger, extra cell battery, tweezers, matches, garden gloves, flashlight, extra pens, water bottle, bug spray,sunscreen,dry socks (this came in handy just recently), bandaids, hand sanitizer,swag,multi-tool. I also pack change of clothes(keep in car)in case weather changes on us. My partner carries a gripper tool and a long stick to bushwack. Both our hats have lights.
HA! It sounds like a lot but we have used just about everything at least once. I just saw a post about the mirror, yesterday and will be adding that too