Arduino page for it here.

Download from here or just install TimerOne using the Arduino libraries manager

Using the Timer 1 Library For a Simple IRQ Timer

#include <TimerOne.h>

  //Set the Timer 1 IRQ frequency
  Timer1.initialize(10000);      //Set the timer period in uS (this function will attempt to match using the available prescaller settings
  
  //Set the timer 1 IRQ fucntion to be called
  Timer1.attachInterrupt(timerIsr); // attach the service routine here
  
  //Timer1.stop();            //stop the timer
  //Timer1.start();           //stop the timer
  //Timer1.restart();         //set the clock to zero
  //Timer1.setPeriod(10000);  //Set the timer period in uS (this function will attempt to match using the available prescaller settings

//*****************************************
//*****************************************
//********** TIMER 1 IRQ HANDLER **********
//*****************************************
//*****************************************
void timerIsr()
{
    
}