Storing the value of a dynamic checkbox into the state hook

I have a form component that displays all the contacts in a stateful array as checkbox options. when the associated checkbox is checked, the contact should be passed into newGroup.groupContacts, and likewise should be removed if unchecked. What would the syntax be for including performing this action within handleCheckbox?

const CreateGroupForm = props => {

    const defaultForm = { id: null, groupName: '', groupContacts: [] }

    const [newGroup, setNewGroup] = useState(defaultForm)

    const handleInputChange = event => {
        const { name, value } = event.target 
        setNewGroup({ ...newGroup, [name]: value })
    }

    const handleCheckbox = event => {
        console.log('called')
        const {value} = event.target
        console.log(event.target)
        setNewGroup({...newGroup, groupContacts: [...newGroup.groupContacts, value] })

    }

    const handleSubmit = event => {
        event.preventDefault()

        if (!newGroup.groupName || !newGroup.groupContacts) return

        props.addGroup(newGroup)

        setNewGroup(defaultForm)

    }

    return (
        <div>
            <h2>Create a Group</h2>
            <Form onSubmit={handleSubmit}>
                <Form.Group >
                    <Form.Label>Group Name</Form.Label>
                    <Form.Control 
                        type="text" 
                        name="firstName" 
                        onChange={handleInputChange} 
                        placeholder="First Name" 
                        value={newGroup.name} 
                    />
                </Form.Group>
                <Form.Group >
                {props.contacts.map(contact => (
                    <div className="mb-3" key={contact.id}>
                        <Form.Check 
                            onChange={handleCheckbox}
                            type='checkbox'
                            label={`${contact.firstName} ${contact.lastName}`}
                            value={contact}
                        />
                    </div>
                ))}
                </Form.Group>
                <Button type="submit">Submit</Button>
                <Button>Cancel</Button>
            </Form>
        </div> 
    )
}

export default CreateGroupForm