Yaakov was born in Israel on December 23, 1930 to Hanna née Dahan and Michael (Makhluf) Hamu. His father made aliyah in eighteen from Morocco, while his mother was born in Tiberias. Yaakov was the youngest in the Hamu family, which would be renamed Michaeli. He attended the elementary school in Binyamina. At the end of his studies, he joined a transportation cooperative, where he worked as a truckdriver.
In 1945, Yaakov joined Lehi in Binyamina. At the beginning, he was involved in putting up posters and training with firearms. From 1946 on, he occupied himself with guard duty, security and demolition activities against the British occupiers. He mined the road from Binyamina to Hadera and blew up the Roman bridge (train trestle) by the Binyamina quarry. After the explosion, the British used railroad ties to fix the bridge, but two days later Lehi members (including Yaakov) burned the bridge, making it unusable for a long time.
In 1947, he took part in several anti-Arab activities, including at what is now Caesarea (then el-Bara) and Regavim (then Qannir).
Afterwards, he participated in a Lehi commando course at Pardes Katz. This course included training in navigation, first aid, firearms and demolitions. On February 29,1948 he was part of the operation to blow up the train from El Qantara, Egypt to Beirut. At Binyamina, Lehi members blew up the track, halting the train.
When the State was established, Yaakov followed most of his fellow Lehi members in enlisting in the 8th Brigade (the old man’s brigade), in Battalion 89, in Company A, under the command of Yaakov “Blond Dov” Granek. He fought in many of the campaigns in the south: Operation Danny, Operation Death to the Invader, Operation Gayis, Operation Yoav, Operation Eight and Operation Assaf.
In December 1948, in Operation Horeb, Yaakov was injured at Auja el-Hafir and released from the unit.
Yaakov continued to do reserve duty, as a truckdriver. He took part in the Sinai War, the Six-Day War and the Yom Kippur War.
In 1949, he married Yaffa, whom he had known since they were both young and was a fellow Lehi member. Yaakov drove a truck for thirty years, then became an account manager. They had three sons, grandchildren and great-grandchildren.