If you define the harpoon as something which is attached to the boat, then they didn't use this kind of contraption. But I use the definition that harpoon is the the spear with a strong line attached. And they used it - they attached it to a bladder or bag or some other float, to both impede movement of the animal, and to retrieve it easier from the water later.
Actually I use "harpoon" for fish spears in general, because many archaeologists use this word in this meaning. The oldest harpoon named as such is made from deer antlers, it was initially dated 6000-8000 years (later revised to ~12000 after carbon dating), and of course there is no shaft anymore (because it was wooden), it's named the Leman and Ower Bank Harpoon, and was tied to a Kunda culture, which are by scientists considered ancestors (or rather one of ancestors) of Sami. Still, if the carbon dating is correct, it was made by some even older culture...
Also only one group of Sami regularly pursues whales (Sjo Sami, a.k.a Sea Lapps), others do it only when the whales are in the shallow coastal waters. But all groups living near seal hunt seals.