This sample shows how to consume the Windows 10 API from .NET Core and .Net Framework projects.
To access Win10 APIs you need to have the Windows SDK installed. You can add it from the Visual Studio setup or download from here
You can reference the winmd by using the Add Reference dialog or adding the following to your .csproj file:
<ItemGroup>
<Reference Include="Windows">
<HintPath>$(MSBuildProgramFiles32)\Windows Kits\10\UnionMetadata\10.0.16299.0\Windows.winmd</HintPath>
<Private>False</Private>
</Reference>
</ItemGroup>