You can move your Micro.blog account and its followers to a Mastodon server. When you do this, you will have a new fediverse handle at Mastodon.
Any followers on Micro.blog (including people who mostly only use Micro.blog) will migrate to your new account. Followers on Micro.blog who have fediverse support disabled will not be migrated.
What about posts? Micro.blog can import Mastodon posts, but Mastodon has no post import functionality. When you migrate from Micro.blog to Mastodon, you will essentially be starting over with only the posts that already existed on your Mastodon account.
To initiate a migration, first link the account on your old server (Micro.blog) to your new server (Mastodon) with an alias. In Mastodon, click on Account → “Moving from a different account” → “create an account alias”:
Then go to Micro.blog to start the migration under Account → View Fediverse Details → “Migrate Away…”:
Micro.blog will notify all of your followers to start following the new Mastodon account. It may take hours or days to completely migrate if you have many followers. You should see the follower count on Mastodon start to increase.