Hirelings & Henchmen

Players Handbook (page 39)

At any time, a character may attempt to hire various different sorts of workers, servants, or guards. The success of such hiring is entirely dependent upon availability of the type desired, wage and bonus offers, and to some extent the character’s charisma.

House Rule

No they can't. Not for a while yet. Minimum 10th level before the player can consider any hirelings or henchmen.
For specific adventures, the party may be able to hire a specialised skilled NPC. But they will never be under direct command of a player character.