How to use $root.$on to catch an emit from another component in Vue3?

Question

In Vue2 i was using $root.$emit and $root.$on among components, but in Vue3, i cant find the substitute for $root.$on .

    //ComponentA.vue
    this.$root.$emit('code-fulfill', response.unique_key);

    //ComponentZ.vue
    this.$root.$on('code-fulfill', (code) => {
       this.code = code;
    });

how to do the same in Vue3 ?

i know how i can do do the emit,

//ComponentA.vue
<script setup lang="ts">

const emit = defineEmits(['update-number'])
//then 
emit('update-number', 4455)

//ComponentZ.vue
**???????**

but the $root.$on i have no idea how to do it, because the root property has no more the property $on.