You can take a cutting now.  You will need to care for the cutting inside until spring.  The websites explain how.  The only difference I would suggest is that vermiculite is a good medium to use because it is sterile and holds moisture well at the root level.  It is also helpful at the early cutting stage to use a clear plastic tent to help with moisture control at the early rooting stage.  See the websites for more details:
1. https://homeguides.sfgate.com/grow-arborvitae-cuttings-21578.html
2. https://content.ces.ncsu.edu/plant-propagation-by-stem-cuttings-instructions-for-the-home-gardener
3. https://growingthehomegarden.com/propagating-arborvitae/

Never mind I see that you said to care for it inside until spring! thanks!

Thank you so much Mary!