Is there any way to input text in Apple Watch

The above answer has no code, just a link to Apple's awesome XD documentation. You can launch a speech recognition menu with some voice options using this code (WatchOS2, iOS 9.2.1):

//LAUNCH VOICE DICTATION (physical device only)
    func launchVoiceDictationMenu(){
        self.presentTextInputControllerWithSuggestions(["Hello","Goodbye","Hey"], allowedInputMode: WKTextInputMode.Plain,
            completion:{(results) -> Void in
                let aResult = results?[0] as? String
                print(aResult)
        })
    }

Update with swift 3 watchOS 3 Scribble mode

presentTextInputController(withSuggestions: ["watchOS3"], allowedInputMode:   WKTextInputMode.plain) { (arr: [Any]?) in
        print(arr ?? "Not find")
    }

With watchOS 3 welcome the new "scribble" mode

[self presentTextInputControllerWithSuggestions:@[@"watchOS3"]; allowedInputMode:WKTextInputModePlain completion:^(NSArray *array){

    if (array != nil) {

        for (int i=0; i<[array count]; i++) {

            NSString *str = [array objectAtIndex:0];

            NSLog(@"%@",str);
        }

    }

}];

Yes, you can input text in Apple Watch using dictation (the watch has a microphone) or by selecting an emoji right on the screen. From Apple Documentation:

WatchKit provides a standard modal interface for retrieving text input from the user. When presented, the interface allows the user to enter text via dictation or to select from a standard set of phrases or emoji.

Swift 4

@IBAction func ReplyWithTextInputController(){

    let phrases = ["OK", "I'm busy.", "Where are you?", "Thanks."]

    presentTextInputController(withSuggestions: phrases,
                                    allowedInputMode: WKTextInputMode.allowEmoji, completion: { (result) -> Void in

                                        guard let choice = result else {
                                            return
                                        }
                                        let suggestion = choice[0]
                                        print(suggestion)

                        })

}