By definition, exempt workers are paid by salary, which means that they get the same amount of pay per week regardless of how many hours they work in a week. Deducting pay from an exempt employee for absences of less than one day is illegal. You can, however, "dock" an exempt employee's pay for an absence of a whole day.
If an exempt employee calls in sick and plans on being out for the entire day, you can "dock" his or her pay for the whole day and make up for the loss from a sick or vacation leave plan, if you offer those kinds of benefits.
If you do dock an exempt employee for any reason, other than for a major safety violation, that employee loses their exempt status for that pay period, not just that week. If that occurs, then you will have to pay any overtime to that employee that may be due for that pay period. If you make a habit of "docking" exempt employees for absences of less than one day, you risk losing the exemption completely, which could make you liable for back overtime pay over a longer period of time.