父组件

<messageForm @createMsgCallback="addCreateMsg" :name="sendForm.name"></messageForm>

 子组件

props:{
      name:{
        type:String
      }
},

computed: {
      computedName(){
        return this.name
      }
    },
    watch:{
      'name':function(val) {
        console.log(val);
        this.sendForm.name = val
      }
},