How can I use Formik data as an object variable

[KeremShtyn]

I want to assign an object and use its variable with Formik like below

const formik = useFormik({
initialValues: {
email: 'johndoe@example.com',
password: 'john',
users:[{
firstName: "123",
secondName: "",
}]
},

However, I do not actually know how to handle changing for data value

<div>
  <form onSubmit={formik.handleSubmit}>
     <TextField
      fullWidth
      id="fistName"
      name="user.firstName"
      label="First Name"
      type="text"
      value={formik.values.users.map(user => user.firstName)}
      onChange={formik.handleChange}
    />
     <Button color="primary" variant="contained" fullWidth type="submit">
      Submit
     </Button>
    </form>
</div>

Can anyone help me?