Are you looking for the best alternative
multitasking for iOS? Or want to replace the stock App Switcher and want to
have something new then Phenomenon tweak will be the best for you. 
Phenomenon is the nice app switcher replacement tweak which allows users to access the new multitasking interface on iOS devices.
Phenomenon
is the nice app switcher replacement tweak which allows users to access the new
multitasking interface on iOS devices.
After installing this tweak you can have
option to configure from setting app in the tweak preferences which offers a
number of features like enabling or disabling the switcher to 3D or to main,
invoke action, use small CC and enable or disable vibration on it.
Tweak Name : Phenomenon
Author: SharedRoutine
Repo: BigBoss
Price: $2.99
Description: Phenomenon is a new and
fresh App Switcher that comes with a really innovative and useful design. It
allows you to invoke it using a 3D Touch on the left side, via a menu double
press or an activator gesture (which is completely optional). This allows you
to either use Phenomenon as a fully replacement or simply as a useful
addition to the default Multitasking Switcher.

Phenomenon comes with some cool
additional features such as “remove and close all switcher apps” by long
pressing or force touching an app item. You can also setup Phenomenon to
vibrate on invoking the switcher.

Users can also setup Phenomenon to
vibrate the device whenever it is invoked, which gives a nice feel when using
the tweak on the iPhone. Phenomenon also gives users the ability to choose
between a smaller Control Center and the normal Control Center for faster
access.
Compatible: Supports all iPhone, iPad
and iPod touch running iOS 9 or later.
How to install Phenomenon on iPhone/iPad
  • Simply open Cydia > Tap on
    Search and type the name of the Cydia tweak Phenomenon and Tap install. 
  • Respring your device because the
    tweaks may not work properly if you do not respring or reboot your device.
  • Now Go to Settings > Scroll down and
    Select Phenomenon.

In the tweak preferences assign Activator gesture
you want, enable or disable the tweak.
That’s it. You can now quickly access
new dimension of multitasking on your iPhone and iPad.
If you are not yet jailbroken then
follow this step by step guide on How to jailbreak iOS 9.0.2-9.1 using Pangu?