This code disables F12 key and the shortcut ctrl shift i combination

Blogger - Disable F12 dev tools and key combination

//disable F12 Key and Ctrl + shift + I combination
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
<script>

$(document).keydown(function (event) {
    if (event.keyCode == 123) { // Prevent F12
        alert('Content is protected\nYou cannot view the Dev Tools.');
		return false;
    } else if (event.ctrlKey && event.shiftKey && event.keyCode == 73) { // Prevent Ctrl+Shift+I        
        alert('Content is protected\nYou cannot view the Dev Tools.');
		return false;
    }
});
</script>