You need to activate the accessibility function, Voice Over, on your phone.
# Connect your iPhone, to a computer with iTunes installed.
# In iTunes, select your device.
# From the Summary pane, click Configure Accessibility in the Options section at the bottom.
# Select the Voice Over and click OK.
# Double tap on the Press home to open text.
Once you pass the initial step you can turn voiceover of.
It worked for me on iOS 12.1.0
(source: https://apple.stackexchange.com/questions/284345/how-do-you-activate-an-iphone-with-broken-home-button-ios-10)