Hobb was a pet form of the name Robert (where there is a mention of Hobb). The Norman invasion in 1066 brought many names to England, but the locals had trouble pronouncing the Norman version of a preceding "R" so they used "H" in many cases, which was easier for them to say. That is why Dick became a nickname for Rick (Richard), and Hobb was substituted for Rob (Robert).
Hob, Hopp, Hobbin, Hoblin, Hobling, Hoblyn are variations. Patronymic forms include Hobbes, Hobbs, Hobbiss, Hobbis, Hobson, Hopson, Hobbins. Hopkins: English Patronymic name...At the time of the conquest, the Normans brought the name Robert to England, and it had several pet forms that became the basis for surnames. Rob (which we still use), Hob, and Dob, were all pet names for Robert.
Hobbs and Hobson were drawn from Hob, and Hopkins was yet another variation. Hopp is generally a variation of the English patronymic name Hobb, which was a medieval given name spelled alternately Hobbe, and Hobb, which was a pet form of the given name Robert. Hob is another variant, while diminutive forms are Hobbin, Hobling, Hoblyn , and Hobbes, Hobbs, Hobbis, and Hobbiss are patronymic variations.
As a name of German origin, Hobb is likely a spelling variation of the Low German name Hoppe.