You can control VoiceOver using an Apple Wireless Keyboard paired with iPhone. See Apple Wireless Keyboard.
VoiceOver Help speaks keys or keyboard commands as you type them. You can use VoiceOver Help to learn the keyboard layout and the actions associated with key combinations.
Use VoiceOver keyboard commands to navigate the screen, select items, read screen contents, adjust the rotor, and perform other VoiceOver actions. Most keyboard commands use the Control-Option key combination, abbreviated in the table below as “VO.”
VoiceOver keyboard commands
VO = Control-Option
Read all, starting from the current position: VO–A
Read from the top: VO–B
Move to the status bar: VO–M
Press the Home button: VO–H
Select the next or previous item: VO–Right Arrow or VO–Left Arrow
Tap an item: VO–Space bar
Open the Item Chooser: VO–I
Double-tap with two fingers: VO–”-”
Select the next or previous item specified by the rotor: VO–Up Arrow or VO–Down Arrow
Adjust the speech rotor: VO–Command–Left Arrow or VO–Command–Right Arrow
Adjust the setting specified by the speech rotor: VO–Command–Up Arrow or VO–Command–Down Arrow
Mute or unmute VoiceOver: VO–S
Switch apps: Command–Tab or Command–Shift–Tab
Turn the screen curtain on or off: VO–Shift–S
Turn on VoiceOver help: VO–K
Return to the previous screen, or turn off VoiceOver help: Escape
Quick Nav
Turn on Quick Nav to control VoiceOver using the arrow keys.
Turn Quick Nav on or off: Left Arrow–Right Arrow
Select the next or previous item: Right Arrow or Left Arrow
Select the next or previous item specified by the rotor: Up Arrow or Down Arrow
Select the first or last item: Control–Up Arrow or Control–Down Arrow
"Tap” an item: Up Arrow–Down Arrow
Scroll up, down, left, or right: Option–Up Arrow, Option–Down Arrow, Option–Left Arrow, or Option–Right Arrow
Adjust the rotor: Up Arrow–Left Arrow or Up Arrow–Right Arrow
You can also use the number keys on an Apple Wireless Keyboard to dial a phone number in Phone or enter numbers in Calculator.
Single-letter Quick Nav for the web
When you view a webpage with Quick Nav enabled, you can use the following keys on the keyboard to navigate the page quickly. Typing the key moves to the next item of the indicated type. To move to the previous item, hold the Shift key as you type the letter.
Heading: H
Link: L
Text field: R
Button: B
Form control: C
Image: I
Table: T
Static text: S
ARIA landmark: W
List: X
Item of the same type: M
Level 1 heading: 1
Level 2 heading: 2
Level 3 heading: 3
Level 4 heading: 4
Level 5 heading: 5
Level 6 heading: 6