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.
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 may need an electrician for this.
A broken ceiling fan motor and a house fire are obviously not ideal outcomes however there is some good news.
The wall dimmer switch reduces power flow and interferes with the fan control.
The new switch does require an additional electrical wire.
Replace the wall dimmer switch with an on off switch.
An example of this is that the motor in your fan could be damaged and rendered useless.
By all means you can connect a ceiling fan directly to a dimmer switch but you may run into problems along the way.