You cannot use a dimmer switch on a fan motor but you can find fan speed controllers.
Can you put a ceiling fan on a dimmer switch.
The wall dimmer switch reduces power flow and interferes with the fan control.
The new switch does require an additional electrical wire.
A broken ceiling fan motor and a house fire are obviously not ideal outcomes however there is some good news.
By all means you can connect a ceiling fan directly to a dimmer switch but you may run into problems along the way.
If your ceiling fan has wiring already in place where you have a separate switch for fan control then you can have the separate controls wired to independent switches.
You can install a ceiling fan light dual dimmer switch to operate the fan speed and light intensity from the original wall switch location.
In this circumstance the light kit could be connected to a dimmer switch and the fan motor connected to a toggle switch.
You may need an electrician for this.