Holding positions in industry while being a professor
Many possibilities:

Sabbaticals,

leaves of absence,

some Universities have "close" contacts with industry and some faculty have combined teaching / research roles...

Some engineering Universities really value faculty who have actually done real work and students appreciate that as well. Nothing like having someone talk about sensors and issues with sensors like getting temperature readings from a brake disc that is glowing red while spinning at 10K rpm... Compared to those "academics" that only ever push paper...

Some Universities even "use" final year engineering students to do funded research (their final year project) for particular issues using University machines as they have helped purchase said machines etc