run function in dynamic component when a function is executed in parent angular

I need to execute a function when a function in the parent component of dynamically created component is executed without changing the parent component.

Do you have any idea for me how to tell in child to execute a function when the function is run in the parent?

1. You can override the function of de parent (if the function is public) if inject the parent in child(*)

   If you has in parent a function

     doSomething()
     {
       console.log("I am parent")
     }
   

   In your child you write

     constructor(@Optional() @Host() parent: ParentComponent) {
       parent.doSomething = () => {
         console.log("I am parent") //make the same of the parent
   
         console.log('I am child'); //and make something more
       };
     }
   

   see a stackblitz

2. Another is make the same using a directive

3. Or extend the parentComponent creating a new Component that extends from Parent

(*)Really I don't suggest this approach, but if you can not "touch" the parent I can not imagine another way