How to align the header and button on the same line using bootstrap 4

You can just use two .col-'s, to place them on one line.

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.bundle.min.js" integrity="sha384-u/bQvRA/1bobcXlcEYpsEdFVK/vJs3+T+nXLsBYJthmdBuavHvAW6UsmqO2Gd/F9" crossorigin="anonymous"></script>
<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-WskhaSGFgHYWDcbwN70/dfYBj47jz9qbsMId/iRN3ewGhXQFZCSftd1LZCfmhktB" crossorigin="anonymous">
<div class="container">
    <div class="get-quote">
        <div class="row">
            <div class="col-sm-10 col-12">
                <h3 id="quote">IN HOUSE EMBROIDERY AND HEAT TRASNFER</h3>
            </div>
            <div class="col-sm-2 col-12">
                <button type="button" class="btn btn-primary pull-right">Get Quote</button>
            </div>
        </div>
    </div>
</div>

Add d-flex class on col-md-12 div.

Also add ml-auto on button to right align the button

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.bundle.min.js" integrity="sha384-u/bQvRA/1bobcXlcEYpsEdFVK/vJs3+T+nXLsBYJthmdBuavHvAW6UsmqO2Gd/F9" crossorigin="anonymous"></script>
<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-WskhaSGFgHYWDcbwN70/dfYBj47jz9qbsMId/iRN3ewGhXQFZCSftd1LZCfmhktB" crossorigin="anonymous">
<div class="container">
  <div class="get-quote">
    <div class="row">
      <div class="col-md-12 d-flex">
        <h3 id="quote">IN HOUSE EMBROIDERY AND HEAT TRASNFER</h3> 
       <button type="button" class="btn btn-primary ml-auto">Get Quote</button>
      </div>
    </div>
  </div>
</div>