Just the same as what should be but change the button component to be label like so
<form id='uploadForm'
action='http://localhost:8000/upload'
method='post'
encType="multipart/form-data">
<input type="file" id="sampleFile" style="display: none;" />
<Button htmlFor="sampleFile" component="label" type={'submit'}>Upload</Button>
</form>