Can I play a unit to a battlefield if from the trigger of Baited Hook if I sacrificed the only unit at that battlefield?

No, you cannot play the unit to that battlefield.

According to FAQ #4776, FAQ #4281, and FAQ #5231, when you use Baited Hook to kill your only unit at a battlefield, you immediately lose control of that battlefield. Because you no longer control the battlefield by the time Baited Hook finishes resolving and you would play the new unit, it is no longer a legal target for placement.

Sequence of Events

1. Activation: You activate Baited Hook by paying its costs (1 Energy, 1 Order Power, and Exhausting the Gear). You declare a target friendly unit at the battlefield.
2. Resolution: Baited Hook begins to resolve. It kills the targeted unit.
3. Control Loss: Because that was your only unit at that battlefield, you immediately lose control of the battlefield.
4. Finalization: Baited Hook continues to resolve, allowing you to look at the top 5 cards of your deck and choose a unit to play.
5. Placement: When you attempt to play the chosen unit, you must select a valid battlefield. Since you no longer control the battlefield where the original unit was killed, you cannot play the new unit there.

As clarified in FAQ #6563, the unit you find with Baited Hook does not finalize until after the ability finishes resolving. By that time, the battlefield is already uncontrolled, making it an illegal destination for the new unit.