How did Babidi/Dabra detect the Z senshi's ki?

[SSJ2]

In the Namek arc, Vegeta says that the humans could suppress "all the way to zero"... so how did Babidi/Dabra know that they were on the rock?

 

[Lightsworn]

They probably used some magic to locate them there.

 

[Zippy]

They either felt them comming (since they flew) and when their ki dissapeared they figured they arrived

Or babidi used some scheme he can make people see stuff that isnt infront of em so idk maybe he can do that for himself, i guess he already knew shin was comming he didnt seem very suprised when he saw him

 

[Let's Go Fearless!]

They didn't sense them but it's like they just knew who followed Yamu and Spobitch.

 

[withheldforprivacy]

Toriyanma warned them.