Add native files from NuGet package to project output directory

I'm trying to create NuGet package for a .Net assembly which does pinvoke to a native win32 dll.I need to pack both the assembly and the native dll with the assembly added to the project references (no problem at this part) and the native dll should be copied into the project output directory or some other relative directory.

My questions are:

1. How do I pack the native dll without visual studio trying to add it into the references list?
2. Do I have to write an install.ps1 for copying the native dll? If so how can I access the package content for copying it?