Alternative to the Windows SDK's <windows.graphics.directx.direct3d11.interop.h> that works well with C++/WinRT.

direct3d11.interop.h

#include <winrt/windows.graphics.directx.direct3d11.h>

extern "C"
{
    HRESULT __stdcall CreateDirect3D11DeviceFromDXGIDevice(::IDXGIDevice* dxgiDevice,
                                                           ::IInspectable** graphicsDevice);

    HRESULT __stdcall CreateDirect3D11SurfaceFromDXGISurface(::IDXGISurface* dgxiSurface,
                                                             ::IInspectable** graphicsSurface);
}

struct __declspec(uuid("A9B3D012-3DF2-4EE3-B8D1-8695F457D3C1")) 
IDirect3DDxgiInterfaceAccess : ::IUnknown
{
    virtual HRESULT __stdcall GetInterface(GUID const& id, void** object) = 0;
};

inline auto CreateDirect3DDevice(IDXGIDevice* dxgi_device)
{
    winrt::com_ptr<::IInspectable> d3d_device;
    winrt::check_hresult(CreateDirect3D11DeviceFromDXGIDevice(dxgi_device, d3d_device.put()));
    return d3d_device.as<winrt::Windows::Graphics::DirectX::Direct3D11::IDirect3DDevice>();
}

inline auto CreateDirect3DSurface(IDXGISurface* dxgi_surface)
{
    winrt::com_ptr<::IInspectable> d3d_surface;
    winrt::check_hresult(CreateDirect3D11SurfaceFromDXGISurface(dxgi_surface, d3d_surface.put()));
    return d3d_surface.as<winrt::Windows::Graphics::DirectX::Direct3D11::IDirect3DSurface>();
}

template <typename T>
auto GetDXGIInterfaceFromObject(winrt::Windows::Foundation::IInspectable const& object)
{
    auto access = object.as<IDirect3DDxgiInterfaceAccess>();
    winrt::com_ptr<T> result;
    winrt::check_hresult(access->GetInterface(winrt::guid_of<T>(), result.put_void()));
    return result;
}