How do I detect mouse movement with UserInputService?

I had assumed It would be a part of InputBegan like:

uis = game:GetService("UserInputService")
uis.InputBegan:connect(function(input)
	local inputType = input.UserInputType
	print("Input: ", inputType)
	if inputType == Enum.UserInputType.MouseMovement" then
		print("Mouse moved")
	end
end)

but UserInputType is never the MouseMovement Enum. Anything wrong here?