The attackers stormed the residence of Ripon Chakrabarty, a Mathematics lecturer at the Nazimuddin Government University College in Madaripur, and attacked him with lethal weapons this evening, police said.
The residents at the neighbourhood grabbed one of the attackers while others fled from the scene.
"The detained attacker is now being grilled in our custody. We suspect he could be a member of a militant group," Madaripur police superintendent Sarwar Hossain told PTI.
Ripon is being treated at a state-run hospital in southwestern Barisal.
Suspected Islamists killed a number of secular activists, four Hindus and other minorities across the country in recent months, prompting authorities to launch a nationwide anti-militant clampdown since Friday.