Turnigy ESCs in particular will beep rapidly if the throttle is set to a position higher than that at which they were calibrated.
Turn down your throttle until the ESCs stop beeping, and make a note of this setting as the upper limit for your ESCs' current calibration. If this throttle setting is too low to achieve your desired flight performance, you will need to recalibrate the ESCs to a higher setting.
Update: Please note that when using HoverflyPRO+GPS firmware version 4.8 and higher, the HoverflyPRO itself will beep constantly while it is armed and on the ground. This is a safety feature to warn the pilot and bystanders that it is unsafe to approach the aircraft.