BlenderDiplom has a series of tutorials that cover working with the new Simulation nodes in Blender.

Blender’s Geometry Nodes got a simulation addition not too long ago. Simulation Nodes in Blender are Geometry Nodes that can create custom physical simulations through graphed node setups.

Here, BlenderDiplom’s Gottfried Hofmann attempts to make simulation nodes less daunting. The tutorial series shows how sim nodes work from all aspects by creating a particle system from scratch.

Also related, visit this tutorial from Jimmy Gunawan, which shows how to use the Geometry Proximity inside a Simulation Zone with Blender Geometry Nodes.