Can I use preCICE to simulate a droplet impacting on an elastic substrate?

In my view, at the moment, this is partially possible.

Dynamic meshes (I assume you will need adaptive mesh refinement) are under development, potentially coming in preCICE v3 later this year: Dynamic Meshes · GitHub (cc @fsimonis)

Multiphase FSI with interFoam and CalculiX and static meshes is already possible. A tutorial for that is under review (on my list at the moment): https://github.com/precice/tutorials/pull/279

If this is a project without time pressure (e.g., you are now starting your PhD), you could already start by setting up a static mesh and gradually add features later.

If you want a simple and documented solution right now, this is not available.

Note that both FSI and multiphase are challenging problems by themselves, so coupling them could have unexpected challenges as well.