You can export the calendar data from Thunderbird in iCal format. Thunderbird understands this (link) as does Evolution (link). You might need to update to a newer version of Evolution for this to work, due to improvements in the iCal data store manager component of Evolution.
The situation is the same for your mail data, except that you'll want to use
mbox format in all likelihood.
On the tiny chance that the
mbox transfer doesn't work properly — very tiny, since
mbox is one of the oldest, simplest, most well-understood file formats in existence — you could try migrating Thunderbird to Maildir format first, then importing from that. But again, I doubt you'll need to go to such lengths.