<button>Заказать <span>10%</span></button>

button {
  border: none;
  background-color: #CB0411;
  color: #fff;
  padding: 8px 15px;
  border-radius: 5px;
  position: relative;
}
button span{
  position: absolute;
  display: block;
  background-color: blue;
  border-radius: 50%;
  width: 20px;
  height: 20px;
  padding: 8px 10px 5px 5px;
  top: -10px;
  right: -20px;
}