Depending on what scoot you’ve got - I’m not sure about other models, but the 125cc models have a biggish oil drain plugs which hold the oil sieve in place. That outlet is quite close to the filler hole.
Maybe you can just drain the oil, remove that big plug, and try to hook the pen out with a piece of wire. If the filler- and drain holes on your scoot is located at the same locations as on my 125, the pen should be lying quite close to that big plug.