Its rather easy to do. And can be done several ways, so ill just comment on one of them here.
If you make an event that triggers every X nr of ticks/Seconds depending on what you like.
And in there you add.
Object.X = random(WindowWidth)
Object.Y = random(WindowHeight)
Since you want it to jump faster and faster, you can add a global variable called "Speed = 15" which will simulate seconds in this example.
In the event "Every X seconds" you set the value to this variable:
Every <Speed> seconds
...make object jump
Then in the end of this you just reduce "Speed" with whatever value you feel like.
So the complete code would look something like this:
Global Speed = 15
Event:
Every <Speed> seconds
Object.X = random(WindowWidth)
Object.Y = random(WindowHeight)
Set Speed to Speed - 1 (Will reduce it by 1 second every time it jumps.)