Hayim was born in Aden on 1.5.1924 to Miriam and Zechariah Yefet. The family made aliyah in 1930 and settled in Jerusalem. The family was very religious, with four brothers and four sisters. The father worked for Agudath Israel. Hayim completed the Bene Zion school and the yeshiva high school. He studied law and Eastern studies in Hebrew University, but only for a year. Then his underground duties and daily work to support the family kept him busy. Only after the establishment of the State would he return to his studies.
In 1935, he joined Beitar, and as of 1939 he was an IZL member. The split brought him to Lehi, where he was active until the establishment of the State. He was not the only one in the family to join the underground, as his sister Yona was also in Lehi, and he also had a sister in IZL and a brother in the Hagana. His mother also was inclined to Lehi, and the entire house, in the new Beit Israel neighborhood, became a center for different activities of the movement. There were firearms drills and lectures. At night, groups would go out to distribute Maas, with Hayim being responsible for them while his mother made the glue as well as meals for the participants in the various courses. Blond Dov was a regular visitor, hiding firearms and explosives in the chicken coop. After some time, Hayim was assigned to Department 6, and a connection was made between David Seton and Arab agents in the Old City who provided important information. Meanwhile, another conduit was via Abu Ghosh, as Romek had connections in the village.
Hayim also recruited youths and adults to Lehi. One of these was among the most colorful Lehi personages in Jerusalem: Hillel the Redhead or Hillel the Elder, Avraham Caravani, whose synagogue attic contained an important secret arms cache. He would also use his donkey to transport explosives and firearms.
When the State was established, Hayim enlisted in the IDF and served in the Jerusalem Brigade. He finished his service with the ranks of captain. He and other IZL men refused to swear fealty to the IDF, as they were afraid that they might have to bear weapons against their former underground comrades or violate their oath. For this they were punished.
He married Ziona Bahbash in 1946. They had two sons and a daughter, and numerous grandchildren.
After the war, he returned to his studies at Hebrew University. He completed a young leaders course created by David Seton. Hayim became a journalist for Doar HaYom, HaBoker, Herut, Yedioth Ahronoth and Maariv. He would become the ITIM news agency’s correspondent in the territories. He directed the journalists’ union and Beit Agron, which established Beit HaItona’im. Hayim was one of the founders. He also edited the annual publication of the journalists in the capital and the monthly publications of the Sephardic community. He was a member of various public institutions, volunteering as the chairman of the oversight board of the Meuhedet Health Fund.