Currently, the Pixelbook on its own has no place to store or hold the Pixelbook pen if you own one—there are no magnets or a loop. However, hidden on the madeby.google.com page is a form to receive a free pen loop from Google at no additional charge.
Simply fill out the form complete with your Pixelbook’s serial number, your country (US, UK, or CA), and where you purchased your device from.
The fine print on the page says the promotion is valid from November 11, 2017 to May 31, 2018—so it isn’t exactly new but you definitely still have time. Anyhow, if you own a Pixelbook and pen and would like a free loop to hold your pen (who doesn’t like free stuff?), head over to the source link below to claim yours.
Source: Pixelbook Pen Loop Promotion