Cyclohexane presents a conformational equilibrium in which the axial hydrogens, in red, move to the equatorial position. The equatorial hydrogens, in green, turn to the axial position.

cyclohexane conformational equilibrium 01

In the absence of substituents, both conformations have the same probability of existing and the coformational equilibrium is not shifted.

conformational equilibrium cyclohexane 02

Observe the red arrows to understand how the transition from one conformation to another takes place.