By default, Safari’s Inspect mode is disabled. To use Inspect mode on the Apple Safari browser, you have to activate it in Safari Preferences.
To activate the Develop menu, go to Safari > Preferences, click the Advanced tab, and check the “Show Develop menu in menu bar” box at the bottom.
1. Open Safari preferences
2. Check the develop menu box
After checked the box Develop menu appear in menu bar.
Now you can use Safari Inspect tool.