If you use an Arduino Leonardo then this supports keyboard/mouse emulation via the USB port. But you'd need some way for that to receive key strokes from the laptop. The simplest approach I can think of for that would be a second Arduino (any type) plugged into the laptop USB, with a TTL serial connection between the two Arduinos. You would need to run an application on the laptop to enable you to type to the laptop Arduino's COM port - there are plenty of options to choose from there.