Note: iCalendar is an IETF standard (RFC 5545) and not to be confused with Apple iCal.
Note: This article explains how to subscribe to and publish iCalendar feeds, not how to export and import iCalendar files, which would be of limited use.
Doodle to Outlook 2013/2016
With your browser, go to https://doodle.com/account#calendars and copy the link from the “Doodle calendar feed (ics)” section, e.g., http://doodle.com/ics/mydoodle/c441dlaaezup2c1e78tylnjulce5c5xs.ics.
In Outlook 2013/2016, choose Open Calendar > From the Internet..., paste the link copied above, and click OK.
Outlook 2013/2016 to Doodle
If you happen to use Outlook 2013/2016 with Exchange, ask your Exchange administrator for permission and help to publish your calendar(s):
With your browser, go to https://doodle.com/account#calendars and for each Exchange calendar that you would like to view within Doodle, click "ICS Feed - Add a URL" and paste its link into the field and click Add. Afterwards, remember to update your MeetMe settings at https://doodle.com/account#meetme if you have a MeetMe page.
As Microsoft discontinued the possibility to publish a calendar on Office.com one can't connect Outlook 2013/2016 with Doodle without Exchange.