Visible crew/equipment: (Episode 4) After Ian shudders from the apparition he continues to follow The Doctor down the hall, and the camera casts a shadow on Ian. Then, when The Doctor finds the stairs leading to the laboratory he tells Ian he must see what's on the table. Just as Ian states his displeasure at the thought, the boom mic (and its shadow) pops up into view at the bottom of the screen, in front of Ian. (00:05:15)
Visible crew/equipment: (Episode 5) When Vicki is in the jungle she happens upon the TARDIS and bangs on the door begging to be let in. In the next shot we can see the boom pole/mic hovering in the background, then a hand appears which seems to guide the actress to head in that direction. (00:07:45)
Visible crew/equipment: (Episode 5) After The Daleks plan to organize a full-scale search of the jungle at daybreak, when it cuts to The Doctor and Ian, the shadow of the boom mic moves around at the left side of the screen. (00:16:35)
Visible crew/equipment: Near the end of episode five as The Daleks plan their attack, a BBC camera can be seen in the background on the right. (00:21:20)
Visible crew/equipment: (Episode 6) At the very end, after Vicki and The Doctor have watched Barbara and Ian's return to 1965 on the Time-Space Visualiser, when Vicki hugs The Doctor the moving boom mic casts a shadow at the top, left of the screen. (00:24:30)
Visible crew/equipment: In episode four, when Ian and the Doctor descend the stairs into Frankenstein's lab, you can see a boom operator and mic behind Ian, at the left side of the screen.
Answer: It was never destroyed on-screen; it was intact at the end of the TV movie, and destroyed by the start of the 2005 series. It was destroyed in the novel "The Ancestor Cell," but in a completely different manner to what happened in the series.
DaveJB