import React from 'react'

export default function Parent() {
    const [myState, setMyState] = useState()

    return (
        <div>
            <ChildComponent onChange={setMyState} />

            <p>
                {myState}
            </p>
        </div>
    )
}

import React from 'react'

export default function ChildrenComponent(props) {
    return (
        <select onChange={props.onChange}>
            <option value="0">Cero</option>
            <option value="1">Uno</option>
        </select>
    )
}