The maker hook is a device used by the Fremen for capturing, mounting and steering the giant creatures. It is named for the sandworms, or "Makers" of Arrakis. The actual hooks are long pieces of metal, with a hook at the very end. This allows the rider to hook onto a segment of the worm. These hooks are not to open the segment to begin riding, but to continue riding.
Use of Maker hooks brings the boldness of the Fremen into sharp focus. After activating a thumper to summon a giant Maker, the hookman (first mounter) stood aside from the approaching worm. As the Maker went by, the hookman inserted one hook beneath the leading edge of one of the sandworm's rings, and the other hook at a slightly lower point on the next ring.
The hookman braced himself back on the hooks, rolling upward with the worm as it rotated away from the threat of sand entering the gap opened by the two hooks. Once up, the hookman and followers steered the worm by opening gaps down one side of the beast, prompting it to roll away from the gaps to prevent sand getting in.
Hooks were important in the Fremen culture. A youth who had been first up was entitled to his own hooks; it was one important rite of passage into adulthood. Most Fremen ride the worm by the age of twelve. Paul Atreides could not have united the Fremen tribes of Arrakis had he not been able to use Maker hooks to mount and ride a sandworm - like every other adult Fremen - on his own.