SOURCE

console.log('Vue: ');
console.log(Vue);

new Vue({
    el: '#app',
    methods: {
    handleChange(value) {
      console.log(value); // { key: "lucy", label: "Lucy (101)" }
    },
  },
})

<script src="https://cdn.bootcdn.net/ajax/libs/vue/2.6.9/vue.min.js
"></script>

<!-- 引入样式 -->
<link rel="stylesheet" href="https://unpkg.com/ant-design-vue@1.7.4/dist/antd.css">
<!-- 引入组件库 -->
<script src="https://unpkg.com/ant-design-vue@1.7.4/dist/antd.min.js"></script>


<div id="app">
    <a-select
    label-in-value
    :default-value="{ key: 'lucy' }"
    style="width: 120px"
    @change="handleChange"
  >
    <a-select-option value="jack">
      Jack (100)
    </a-select-option>
    <a-select-option value="lucy">
      Lucy (101)
    </a-select-option>
  </a-select>
</div>