In 2020 for TextField, via functional components:
const Content = () => {
...
const textFieldRef = useRef();
const readTextFieldValue = () => {
console.log(textFieldRef.current.value)
}
...
return(
...
<TextField
id="myTextField"
label="Text Field"
variant="outlined"
inputRef={textFieldRef}
/>
...
)
}
Note that this isn't complete code.