The "Book of Enoch" is properly understood as 1 Enoch. There are a number of other writings that bear this name (2 Enoch, 3 Enoch) which were written centuries later (probably as counter-missionary works), but generally speaking when people refer to the Book of Enoch, it is with reference to 1 Enoch.
As literature of the time (1 Enoch), the NT authors were familiar with its contents, insomuch that it is cited by Jude with reference to Jesus (vv. 13-14),
“It was also about these people that Enoch, in the seventh generation from Adam, prophesied, saying, 'Behold, the Lord has come with many thousands of His holy ones, to execute judgment upon all, and to convict all the ungodly of all their ungodly deeds which they have done in an ungodly way, and of all the harsh things which ungodly sinners have spoken against Him.' These are grumblers, finding fault, following after their own lusts; they speak arrogantly, flattering people for the sake of gaining an advantage.”
What’s interesting is that this citation that Jude alludes to is from 1 Enoch 1:1-10, which is a reference to the “eternal God” who “will tread upon the earth, (even) on Mount Sinai,”
“The Holy Great One will come forth from His dwelling, And the eternal God will tread upon the earth, (even) on Mount Sinai, [And appear from His camp] And appear in the strength of His might from the heaven of heavens. And all shall be smitten with fear And the Watchers shall quake, And great fear and trembling shall seize them unto the ends of the earth. And the high mountains shall be shaken, And the high hills shall be made low, And shall melt like wax before the flame And the earth shall be wholly rent in sunder, And all that is upon the earth shall perish, And there shall be a judgement upon all (men). But with the righteous He will make peace. And will protect the elect, And mercy shall be upon them. And they shall all belong to God, And they shall be prospered, And they shall all be blessed. And He will help them all, And light shall appear unto them, And He will make peace with them'. And behold! He cometh with ten thousands of His holy ones to execute judgement upon all, and to destroy all the ungodly: And to convict all flesh Of all the works of their ungodliness which they have ungodly committed, and of all the hard things which ungodly sinners have spoken against Him.”
Jude utilizes 1 Enoch 1:1-10 (about the eternal God) and applies it to the Lord Jesus. This does not mean 1 Enoch was considered "Scripture" anymore than those passages which Paul cites from pagan poets and philosophers (Acts 17:22-28) were considered "Scripture." The NT authors cited extrabiblical materials that were meaningful to their contemporary audiences.
1 Enoch is valuable for studying Second Temple Judaism, but 2 Enoch, 3 Enoch, etc. are considered counter-missionary works; written by Jews to combat the spread of Christianity.