How to pass value from variable to React component

How can I store this value globally?

For global state, use the redux store. You can dispatch an action to store this label.

Note , as stated in the README ,

myCustomRedrawAccordingToNewPropsHandlerThis function is called if the properties of the wrapper component are changing

So I'm going to share the sketch object to make it explicit. This repaint function will be used to access the parent function that actually dispatches to the redux store.

// sketch
export default function sketch(p) {
  // use custom redraw handler
  p.myCustomRedrawAccordingToNewPropsHandler = function (props) {
    // TODO: replace with actual label
    // get value out
    setInterval(() => props.gotResults(null, "done"), 5000);
  };
}

// action
const key = "p5";
const SAVE_LABEL = `${key}/SAVE_LABEL`;

// action creator
function saveLabel(label) {
  return {
    type: SAVE_LABEL,
    payload: {
      label
    }
  }
}

export default function Sketch(props) {
  // dispatch inside component
  const dispatch = useDispatch()

  function gotResults(error, label) {
    if (error) {
      console.error(error);
      return;
    }

    dispatch(saveLabel(label));
  }

  return (
    <P5Wrapper
      sketch={sketch}
      gotResults={gotResults}
    />
  );
}

// TODO: add reducer

Sandbox example : https://codesandbox.io/s/pedantic-breeze-54mde