SDL_SetRelativeMouseMode and mouse outside window

Is this possible to capture input when I’m outside the window? I was looking for something like SDL_SetRelativeMouseMode, so I can infinitely move cursor.

I tried to use SDL_CaptureMouse but it didn’t work.

Also when in relative mode, mouse seems slower than in normal mode that is, less responsive.

Or some way to emulate this behaviour? I’m testing on Windows.

What I mean is relative mouse mode without window grabbing.