Screenshot of my CodePen demo implementing this pattern of having a departure point and a destination as input fields and a button between them allowing to swap their values. In this case, the two inputs have a cutout where the round button in between them intersects them and a border following this cutout shape.
https://files.mastodon.social/media_attachments/files/113/288/992/804/302/592/original/9cb61aa2435cee36.png