I made a small solution with jQuery to help you, it is not necessary to block the submit button, follow the code below:
    $(function () {
    var $form = $("#ID_FORMULARIO"),
        $ckTermosDeUso = $("#ID_CHECKBOX"),
        $btnSubmeter = $("#ID_BOTAO_SUBMIT");
    // Evento do Click do botão submeter
    $btnSubmeter.on("click", function (e) {
        // Evitando de executar o envio real do formulário.
        e.preventDefault();
        // Verificando se o checkbox foi marcado.
        if ($ckTermosDeUso.is(":checked")) {
            // Bloqueando o botão submeter para evitar vários click's
            $btnSubmeter.attr("disabled", "disabled");
            // Submetendo o formulário.
            $form[0].submit();
            return true;
        }
        else {
            window.alert("Você deve aceitar os termos de uso!");
            return false;
        }
    });
});
							
							
						 
When the button is disabled, it will not perform any function. You must enable the button (by removing the disabled) and after firing click disable function. I still don’t understand your question.
– Jean Gatto
hi @jeangatto, I have a form and the button is enabled when the person agrees to the terms so I wanted to put an alert or a message saying that she forgot to agree to the terms in case she click the button without agreeing to the terms
– Cyber Hacker