SOURCE

<div contenteditable='true'>
  <!-- <div class='checkbox'/><div>sdf</div> -->
  <p>
    <img src='http://oj8dg2zpl.bkt.clouddn.com/2017/1525682317089.png' class='img-cb' />helloword!df
  </p>
  <p>
      <span class='checkbox'></span>another hello
  </p>
  <p>
    <input type='button' value='v'/>手低
  </p>
  <p>
    <input type='checkbox' value='sdsd' checked>&#8203</input>手低
  </p>
</div>

.checkbox {
  background:url('http://oj8dg2zpl.bkt.clouddn.com/2017/1525682317089.png') center no-repeat;
  display: inline-block;
  height: 16px;
  width:16px;
  vertical-align:middle;
  line-height:1;
}

.img-cb {
  height: 20px;
}

input[type=checkbox]:after {
  content: ​
}