While still a young man, Jacoby moved to Oslo, where he made a living writing and producing advertising and illustrations.
He was an illustrator and had a drawing office in Oslo in the early part of the Second World War together with the brothers Trygve and Olav Mosebekk.
The series was reworked after the war and was published under the name Sabotasjegjengen (The Sabotage Gang) in the revived magazine, now renamed Alle Menns Blad.
[4] Jacoby was a close childhood friend of the adventurer and researcher Thor Heyerdahl,[5][6] and he wrote several biographies about him, including Señor Kon-Tiki, which was published globally.
Jacoby's most influential book was Det angår også deg (It Also Applies to You), which deals with Herman Sachnowitz's time as a prisoner at the Auschwitz concentration camp and was written in collaboration with him.
[8][9] In 1984 he published the book Min afrikanske gullalder (My African Golden Age), which describes the adventures of Jacob Matheson (Thor Heyerdahl's half-brother) in Africa.