0.1kWh over how much time? Per day? Per hour? Per week?
Watthours refer to total power used to do something, from a starting point to an ending point. It makes no sense to say that a device needs a certain amount of Wh, unless you're talking about something like charging a battery to full.
Power being used by a device, (like a computer) is just watts.
Think of the difference between speed and distance. Watts is how fast power is being used, watt-hours is how much has been used, or will be used.
If you have a 500 watt PC, for example, it uses 500Wh, per hour. Or 12kWh in a day.