Andy Chase has published a Google Script that will let you automatically post Google Form submissions to a Slack channel. You need to place the script inside the script editor of your Google Forms editor and associate the onSubmit() method with the Form Submit trigger.

// replace this with your own Slack webhook URL
// https://crowdscores.slack.com/services
var webhookUrl = "https://hooks.slack.com/services/****/****/****";

function onSubmit(e) {
  var response = e.response.getItemResponses();

  // Setup 2:
  // Modify the below to make the message you want.
  // See: https://developers.google.com/apps-script/reference/forms/form-response
  var d = e.response.getRespondentEmail() + " | " + response[0].getResponse();

  var payload = {
    payload: '{"text": "' + d + '"}',
  };

  var options = {
    method: "post",
    payload: payload,
  };

  UrlFetchApp.fetch(webhookUrl, options);
}