title: Plotly-Dash: How to code interactive callbacks for hover functions in plotly dash
body: <p>Is it possible to have a text field at the bottom of a graph in dash that displays the text for the point they are on (showing hover data as plain text). So the text box will be able to make changes when users hover over a certain point. I have defined a dcc.Graph component and the app layout but am not sure how to define the callback function for the hoverdata.</p>
  <p>I have used the below code to define dcc.Graph and app.layout</p>
  <pre><code>fig = go.Figure(data=plot_data, layout=plot_layout)
  
  app.layout = html.Div([
      dcc.Graph(figure=fig),
      
          html.Div([
                      dcc.Markdown(id='mpg-metrics')
                  ],style={'width':'20%','display':'inline-block'})
  ])
  </code></pre>
  <p>Any help with the callback will be great. thanks in advance</p>