You can make a treat parcel out of a toilet roll inner. Erin's hamsters 10 toilet roll tube toys shows how, below. They like to have plenty of substrate and will often keep busy moving it around and building little mountains with it or digging in it. You could also scatter feed some of her hamster mix as well as putting it in her food bowl, as they like foraging for food also.
If you make any of the ones using string, then it needs to be sisal string which is safe to chew and be careful with any hanging things so they are hung so they can't get tangled
https://www.youtube.com/watch?v=NuPeyD6w-CI&t=38s