Airport Time Capsule US power cord in Europe?
I remember reading the tech specs for Timecapsule some time ago and it is specified it has a range of 100V to 240V. So it should be fine.

AirPort Time Capsule 802.11ac - Technical Specifications
Electrical and Environmental Requirements

100-240V AC, 50-60Hz; input current: 1.5 amp


You can check this, too.
Here is a link to the Apple TimeCapsule Technical Specifications - please also check if this is your version of Timecapsule.
Have a good trip!